The present invention relates to a method of detecting the position and posture of an object to be handled by sensing the optical image of the object and analyzing it, and an apparatus for performing the method.
Also, the present invention relates to a robot vision system which detects the position and posture of an object to be handled by sensing the optical image of the object and analytically processing it, the detected results being used for controlling the arm mechanism of a robot.
Further, the present invention relates to a robot vision system which is well suited for installation on, especially, the hand of a robot, among robot vision systems which detect the position and posture of an object to be handled in an assembling operation to be executed by a robot.
As an expedient for detecting the position of an object, there has heretofore been a system wherein the whole object is uniformly illuminated and has its optical image converted into an electric signal by the use of an image pickup device such as TV camera, the electric signal is binary-coded on the basis of a certain reference signal, and the binary-coded picture signal is processed. With this system, however, it is necessary that the surface of the object to be handled is greatly different from the background thereof in color or brightness, so only the object can be separated and extracted on a picture by the binary-coding. Moreover, the system cannot detect the position of the object in a depthwise direction. Therefore, in a case where the object needs to be grasped or to have a component mounted thereon as in an assembling operation which is executed by a robot, the object must lie at a known distance from the detector. Accordingly, the system resorting to the binary-coded picture has the disadvantage that the objects to be handled are limited.
As a system for use in automatic welding by a robot, there has been one wherein a light segment detecting head is installed on the hand of the robot, and a detected light segment waveform is arithmetically processed to automatically detect a welding position, as disclosed in "A Visual Sensor for Arc-Welding Robots", Bamba, T., et al., 11th Int. Symp. on Industrial Robots, pp. 151-158 (1981). This system is limited, however, to handling objects characterized by grooves.
Furthermore, in an attempt to apply this system to the assembling operation, an NBS system (VanderBrug, G. J., et. al., "A Vision System for Real Time Control of Robots", 9th Int. Symp. on Industrial Robots, pp. 213-230, 1979) has been devised. In order to detect the position and posture of an object completely in three dimensions with this system, a robot arm carrying the detector thereon needs to be moved so as to view the object from several different angles. This leads to take a long time for the detection.